I had no idea of it's a fact or just a piece of political agitprop until I came to this part:

In the media, Carson has come under fire for controversial comments, including his remarks that Muslims should not be allowed to serve as president, and that Adolf Hitler might have been stopped had the German public been armed.

That's just a lie. It's not just an oversimplification of something someone said, it's a flat out lie. Here is the Meet the Press transcript:

CHUCK TODD: Let me ask you the question this way: Should a President’s faith matter? Should your faith matter to voters?

DR. BEN CARSON: Well, I guess it depends on what that faith is. If it’s inconsistent with the values and principles of America, then of course it should matter. But if it fits within the realm of America and consistent with the constitution, no problem.

CHUCK TODD: So do you believe that Islam is consistent with the constitution?

DR. BEN CARSON: No, I don’t, I do not. … I would not advocate that we put a Muslim in charge of this nation. I absolutely would not agree with that.

CHUCK TODD: And would you ever consider voting for a Muslim for Congress?

DR. BEN CARSON: Congress is a different story, but it depends on who that Muslim is and what their policies are, just as it depends on what anybody else says, you know. And, you know, if there’s somebody who’s of any faith, but they say things, and their life has been consistent with things that will elevate this nation and make it possible for everybody to succeed, and bring peace and harmony, then I’m with them.

"I would not advocate that we put a Muslim in charge of this nation" is not the same as saying that Muslims should not be allowed to serve as president.

With regard to armed Jews in Germany Carson wrote:

German citizens were disarmed by their government in the late 1930s, and by the mid-1940s Hitler’s regime had mercilessly slaughtered six million Jews and numerous others whom they considered inferior … Through a combination of removing guns and disseminating deceitful propaganda, the Nazis were able to carry out their evil intentions with relatively little resistance.

He said to Wold Blitzer of CNN:

"the likelihood of Hitler being able to accomplish his goals would have been greatly diminished if the people had been armed."

The fact is that the Nazis disarmed the German people with special emphasis on Jews, making it a great deal easier - and safer for the Nazis who had to do the actual work - to round them up and send them to death camps. He didn't say that Hitler would have been stopped, not once, never. But if you get your news from the Washington Post, you would beleive the lies.